Field of the Invention
The invention is related to an optical module and a display module, and particularly to a front light module and a display module.
Description of Related Art
In a general reflective display design, a light guide plate is attached above a display module, and a light source is disposed on a lateral side of the light guide plate. Light emitted from the light source may travel within the light guide plate by total reflection, and is refracted toward the display module by a microstructure destroying the total reflection in a visible area. The light refracted toward the display module is then reflected by the display module to a viewer.
Currently, in a white light-emitting diode (LED), an LED chip emitting blue light excites yellow phosphor, and the blue light is mixed with the yellow light generated by the excitation to generate white light. The blue light and the yellow light have different light divergence angles. Generally, the blue light is emitted from the chip and reflected by a package cup for light emission, and has a smaller light divergence angle. The yellow light is generated due to excitation of the phosphor, and has a greater divergence angle.
Due to the difference in divergence angle between the blue light band and the yellow light band, and due to a natural stacked design of a reflective front light module and a market demand for lightweight and compact products, a light coupling region has to be shortened. In a general reflective display, directly in front of the light source, due to its greater divergence angle, the yellow light more easily enters the display module through an optical adhesive layer before entering the visible area. As a result, a part of the yellow light is absorbed so that an image in relatively cool white is likely to be presented directly in front of the light source in the visible area. In addition, obliquely in front of the light source, the whole light divergence angle (including the blue light divergence angle and the yellow light divergence angle) is smaller than that directly in front of the light source, and light emergence is not easier. As a result, the proportion of the yellow light absorbed before entering the visible area is considerably reduced, so that an image in relatively warm white is likely to be presented obliquely in front of the light source in the visible area. Thus, on the side of the light guide plate closer to the light source, a problem of nonuniformity of color of the emitted light is likely to occur.